Faulty car upon purchase

I January 2021 I bought a VW Polo from a dealership (Auto unique) and two weeks later it started overheating, I notified the dealer and they collected the car and offered to fix it. 2 days later they brought it back and it drove fine until it started giving me the same problem 2 weeks later. The dealer then collected the car once again and offered to fix it, they collected the car and told me they fixed it 2 days later, i drove the car for a couple of days and still wasn't fixed. At this point I am upset and requested that they take back the car as it is unreliable and they cannot fix the issue. The dealer is refusing to cancel the contract and I am still within 3 months of purchasing the vehicle. They are offering to once again fix it which will be the 3rd time, as a consumer I must have some way of at least making my request heard.

Please help.